1. Field of the Invention
This invention relates to containers and more particularly to a sealed dispensing tube having a membrane pierced by a needle which passes through the lumen of a nozzle cap threaded to the tube.
2. Prior Art
Product dispensing tubes having a neck with a mouth opening, or a throat, closed by a membrane are well known and are commonly employed, for example, in adhesive containers where, by sealing the container with the membrane, increases in the shelf life of the product is attained. The membrane must be pierced in order to dispense the contents of the container and such piercing is often accomplished by pin or needle-like structures affixed to the cap.
It has been known to have threaded caps on such containers which are equipped either with membrane piercing pins (or needles) on the outside of the cap such that upon unthreading the cap from the container, and inverting the cap, the membrane piercing pin can be pushed through the membrane, or in other instances, the pin is formed on the interior of the cap and a spacer structure is interposed between the container and the cap to prevent the cap from being tightened down sufficiently on the container to pierce the membrane. Upon removal of the cap, the spacer can be discarded, and thereafter by retightening the cap fully on the container, the pin can pierce the membrane. Distinct disadvantages of such cap piercing systems exist. In the first type, the pierced opening is never reclosed and the contents of the container can flow through the pierced membrane unobstructed even when the cap is threaded back onto the container. Although in the second type of structure, the piercing pin will reenter the pierced opening each time the pin is screwed back on, thereby substantially closing the pierced opening, product leakage still can occur around the piercing pin particularly as the opening enlarges after repeated recapping, and then follow the threads of the cap to provide a leakage path to the exterior.
Recently a two-piece cap container has been described having a nozzle defining cap which is permanently affixed to the tube container and extends from the mouth of the container. The cap has a nozzle lumen open to the mouth downstream of the membrane. An overcap which can be threaded to the nozzle cap is provided with an axially movable pin which passes through the lumen of the nozzle when the caps are joined together and which is moveable from a position spaced from the membrane to a position piercing the membrane.
After piercing the membrane, the outer cap can be unthreaded from the nozzle cap thus withdrawing pin from the lumen and allowing the contents of the container to be dispensed through the pierced membrane and through the nozzle. On completion of dispensing, the outer cap can again be threaded onto the nozzle cap with the pin in the nozzle lumen and projecting into the membrane opening. In this type of structure, shown, for example, in U.S. Pat. No. 5,799,829, the teachings of which are incorporated herein by reference, after each use the pierced membrane opening will be reclosed, substantially, by the pin, thus reducing leakage. However, because the nozzle cap is permanently fixed to the tube, usually by being snapped onto the tube, a large open space is provided between the membrane and the tip of the nozzle which can be filled with product which can then leak out between the nozzle cap and the tube neck. This leakage path can vary due to tolerance differences between the normally molded plastic nozzle cap and the container neck, normally made of metal. Because the nozzle cap is fixed to the container, it is not possible to tighten the connection between the container and cap to eliminate leakage paths.
It would therefore be an advance in the art to provide an improved membrane sealed dispensing container utilizing a nozzle cap attached to the container and a pin carrying overcap threaded to the nozzle cap with an acutalable pin to pierce the membrane where leakage paths between the nozzle cap""s exterior and tube interior are blocked.
This invention overcomes the disadvantages of the prior art by providing a threaded tube neck having external threads engaging internal threads in a counter bore of a nozzle cap allowing the nozzle cap to be tightened down on the container neck to eliminate leakage paths due to thread engagement. The nozzle cap is provided with an interior stopper which surrounds a lumen of a dispensing nozzle of the nozzle cap and which projects into the interior of the tube throat through the mouth opening while engaging the inner diameter of the throat at the mouth opening to provide a seal. The stopper terminates in closely spaced relation to the membrane. By tightening the nozzle cap onto the threaded neck of the container until the stopper has engaged and sealed against the throat opening at the mouth, leakage paths between the container interior and the exterior at the container neck are eliminated and the lumen is closed except to the mouth of the tube.
In an embodiment of the invention, a dispensing container formed as a metal tube is provided with a tube neck projecting therefrom terminating in a mouth open to a throat opening. The throat opening is closed by a membrane spaced from the mouth opening and a nozzle cap, formed of plastic is provided with a counter bore at an end thereof having internal threads adapted to mate with external threads of the tube neck, the counter bore terminating at an internal stopper dimensioned to plug the mouth opening when the nozzle cap is threaded onto the tube neck, the stopper having an axial opening therethrough to the lumen of the nozzle. An overcap is threadably connected to the nozzle cap and has an interior bore adapted to sealingly engage the exterior of the nozzle adjacent a dispense end of the nozzle. The overcap carries an actuatable axially movable pin which projects through the lumen of the nozzle and which when depressed pierces the membrane and plugs the dispense opening to the interior of the lumen.
It is therefore an object of this invention to provide an improved membrane sealed container having a dispensing nozzle cap carried at a throat of the container with a pin carrying outercap having an actuatable pin for piercing the membrane with an internal stopper on the nozzle cap plugging the mouth opening of the container.
It is another object of this invention to provide a dispensing container particularly adapted to dispense liquid adhesives employing a metal tube having a neck with a throat blocked by a pierceable membrane closing the throat at a point spaced from a mouth opening to the throat at an end of the neck, the tube being provided with a threadably connected nozzle cap having a lumen extending therethrough open to the interior of the throat, a lumen opening being defined in a stopper formed in the nozzle cap interior which projects into the mouth of the container and seals the mouth except through the lumen.